The invention relates to methods of fabricating electroluminescent displays, and more particularly, to methods of fabricating organic light emitting diode (OLED) displays with multi-mode micro-cavity layers.
Among flat panel displays, organic light emitting diode (OLED) displays exhibit characteristics of self-emission, high brightness, wide viewing angle, high response, simple fabrication process, low power consumption, and good outdoor reliability, and are therefore widely applied in portable computers, notebooks, mobile phones, and personal digital assistances (PDAs).
To achieve full color display, a conventional OLED display comprises OLED elements having red, green, and blue pixels, separately formed on an active matrix substrate. Conventional fabrication methods for OLED displays require precision alignment and a shadow mask process, thus the fabrication process is complicated.
White light OLED displays with color filter thereon are proposed to simplify fabrication. U.S. Pat. No. 6,133,692, the entirety of which is hereby incorporated by reference, discloses a method of fabricating white light OLED displays. FIG. 1 is a cross section of a conventional white light OLED display. A white light OLED display 10 comprises an organic light emitting diode element 11, a multi-mode micro-cavity layer 12, and a color filter 13, disposed on a transparent substrate 14. The organic light emitting diode element 11 comprises an upper electrode 15, at least one light emitting layer 16, and a lower electrode 18. A mirror stack structure 21 is interposed between the lower substrate 18 and color filter 13.
Since the light from the conventional white light OLED display comprises a broadband spectrum, even after passing through a color filter, each red, green, and blue light is still broadband. The colors of the white light OLED display are less saturated than in a conventional tri-color OLED display. Moreover, a color filter of a conventional white light OLED display is organic, and the multi-mode micro-cavity layer is metal or an inorganic material. From a processing point of view, forming an organic color filter at low temperature prior to a micro-cavity layer at high temperature of may complicate the fabrication process, reducing the process window and increasing production costs.